Apparatus fok



ocr. 3, 1939.

c. F. JONES 2,174,788

APPARATUS FOR PHOTOGRAPHIC PRINTING Filed Oct. ll, 1937 6 Sheets-Sheet 1 ATTURNEY Oct. 3, 1.939. C;- F, JONES 2,174,788

APPARATUS FOR PHOTOGRAPHIC. `PRINTING Filed 001. 11, 1957 sheets-sheet 2 IN V EN TOR.

@bor/f5 1/0/765,

ATTORNEY Oct. 3, 1939. c. F. JONES 2,174,788

APPARATUS FOR PHOTOGRAPHIC PRINTING A TTORNEY Oct. 3, 1939. c. F. JONES 2,174,788

APPARATUS FOR PHOTOGRAPHIG PRINTING Filed Oct. ll, 1937 6 Sheets-Sheet 4 /47 IN V EN TOR. /gf/ @bar/f.: da/25.53

BY @il ATTORNEY Oct. 3, 1939. c. F. JoNI-:s 2,174,788

APPARATUS FOR PHOTOGRAPHIC PRINTING Filed oct. 11, 1957 e sheets-sheet 5 nnnnnnnnn pannnnon IN V EN TOR. @af/e5 dans :y

vl 1 l I M n I I BY DUUQUUGHOUU #fr ATTORNEY Oct. 3, 1939.

c. F. JONES 2,174,788

APPARATUS FOB PHOTOGRAPHIC PRINTING Filed Olot. ll, 1937 6 Sheets-Sheet 6 1N V EN TOR. b Off/es /v (Jo/nes) ATTORNEY Patented Oct. 3, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR PHOTOGRAPHIC PRINTING Application October 11, 1937, Serial No. lGSA Claims.

My invention relates to an apparatus for printing on photographic film, and particularly to means for providing suitable illumination at the printing aperture; and it has an especially valu- 5 able application in the printing of lm employed in the making of colored motion pictures.

An object of my invention is to provide a printer for photographic lm in which the intensity of illumination at the printing aperature is accurately controllable.

Another object is to provide a printer for motion picture lm in which the light at the printing aperature may always be of substantially the same color regardless of the intensity to which it is adjusted.

Another object is to provide a printer suitable for simultaneously printing through two negatives onto opposite sides of a motion picture film comprising one or more emulsions.

Another object of the invention is to provide in a printer for motion picture iilm means for quickly and accurately changing the intensity of illumination at the printing aperature to a predetermined value.

Another object is to provide in a printer means for continuously indicating the luminous intensity of the source of illumination of the printing aperature.

A further object of my invention is to provide means in a printer to prevent the accidental exposure of the film during the threading of the printer.

These and other apparent objects I attain in a manner which will. be clear from a consideration of the following description taken in connection with the accompanying drawings, of which:

Fig. 1 is a view of the front of my printer.

Fig. 2 is a View of the back of my printer.

Fig. 3 is a cross-sectional View of the printer taken along the line 3-3 of Fig. 4 in the direction of the arrows as shown.

Fig. 4 is a cross-sectional View of the printer taken along the` line --Li of Fig. 3 in the direction of the arrows as shown.

Fig, 5 is a view from the front of the printer of the mechanism controlling the printing illumination, with the disc in iront partially cut away.

6 is a cross-sectional view of the mechanism of Fig. 5 taken along the line 5-6- Fig. 'Y is a cross-sectional View of a portion oi the mechanism shown in Fig. 5 taken along the line '1 -1, with the rear of the ratchet casing partially cut away.

Fig. 8 is a View of one element of the mechanism of Fig. 6.

Fig. 9 is anew of another element of the mechanism of Fig. 6.

Fig. l0 is a View of a metering spacer employed in the mechanism of Fig. 6.

Fig. l1 is a view in cross-section through a portion of the printer taken along the line iI-il of Fig. l in the direction of the arrows as shown.

Fig. l2 is a view of the contacting device employed in connection with the light change mechanism,

Fig. 13 is a view of a portion of the printer taken along the line l3--i3 in Fig. 3 at the face of the pressure plate in the direction of the arrows as shown.

Fig. 14 is a view of the lower half of the contacting device of Fig. l2 showing a notched negative passing through the device.

Fig. 15 is a cross-sectional view of a portion of the printer taken along the line l5-I5 of Fig. 1 in the direction of the arrows as shown.

In the printing of photographic lm and particularly motion picture iilm in which high standards of quality obtain, it is necessary to provide illumination which is dependent upon the density of the negative through which the light must pass to expose the positive being printed. In the printing of motion picture lm it is desirable that the intensity of illumination at the printing aperature be very accurately adjusted to the proper value. This is true because in motion pictures one scene follows another and if there were serious differences in density of the photographic image between successive scenes it would be extremely unpleasant and the artistic eiect of the picture would be largely lost. In the making of modern motion pictures with a sound track photographically reproduced on the positive nlm, the development of the positive is denitely fixed by the requirements of the sound track, and the density of the positive nlm is then determined practically entirely by the intensity of the illumination employed in printing, assuming the positive emulsion and negative density to be given.

The accuracy with which the intensity of illumination in printing must be xed is greater in the printing of positive film to be employed in the making of colored motion pictures, for not only must the overall density of the picture be considered but the density of the two or more separately colored images must be balanced, or the resulting color of the complete colored film will not be true.

Heretofore it has been customary to change the intensity of illumination at the aperature of a printer by changing the electrical resistance in series with the electric lamp serving as the source of illumination. This change has generally been produced by means of a light change device comprising a large number of electrical resistance units and various contacts by which any chosen resistance might be inserted in the circuit. Generally the device is set up, prior to the printing of a film involving many scenes, with a separate resistance, determined. by the requirements of each scene, ready to be automatically inserted into the lamp circuit when the corresponding scene reaches the printing aperature. It is obvious that such an arrangement contains many contacts, every one of which must function with no resistance of its own if the predetermined circuit resistance is to be secured. Actually, it is found that these contacts do not perform perfectly; in fact they are a constant source of trouble and require continual servicing. These devices present other difficulties also. As they heat, their resistance changes, resulting in further variation of the illumination. Then, a major objection to the resistance method of changing illumination is that as the current through the lamp is reduced the colo-r of the light emitted also changes along with the intensity. This not only results in effective exposures of the film being affected because of the dependence of nlm sensitivity upon color, but also results in different contrasts in the various scenes because, for the same development, the contrast is dependent upon the color of light used in exposure. Ehe latter effect is important in high quality color processes in which variations in contrast may disturb the color balance.

in the printer of my invention I provide means for continuously indicating the luminous intensity of the illumination sources to insure against their deterioration or sudden failure going unnoticed, and I vary the intensity of illumination at the aperture by interrupting the light from the illumination source in different degrees depending upon the illumination required. Thus, the luminous intensity and color of the source remain substantially constant; and since no resistances, contacts, etc., are employed, a prominent source of trouble in commonly used devices is avoided.

The embodiment of my invention illustrated in the drawings is a printer adapted to simultaneously print through two negatives onto a positive film interposed between the two negatives. This printer is particularly useful in printing color films in which case one Vnegative may be that which has recorded the predominantly green or blue portion of the photographed scene and which for convenience will hereinafter be referred to as the green negative, and the other negative may be that which has recorded the predominantly red portion of the scene and which will hereinafter be referred to as the red negative. Between these negatives is interposed at the printing aperture a positive film which may be of duplitized character, i. e., one which has a sensitive emulsion on each side of the supporting base or it may comprise simply a supporting base with one or more emulsions on one side thereof.

In the drawings, referring particularly to Figs. 1 and 2, the frame of the printer is designated by numeral 2&3. Carried by the frame 2E! is a panel 2l supporting the various reels on which the film is carried. Raw positive film stock is carried on the reel 22 and after passing through the printer is taken up on reel 23. The green negative is carried on reel 2li and is, after passing through the printer, taken up on reel 25. The red negative is carried on reel 2G and is, after passing through the printer, taken up on reel 2l, The sound negative is carried on reel 28 and is after passing through the sound track printing aperture, taken up on reel 2:?. In the operation of the printer, the raw positive stock St first passes together with the sound negative Si past the sound track printing aperture, which together with the drive sprocket, gate, illumination means, etc., is generally designated by the numeral 32. The sound negative is then wound up on reel 29 and the raw stock 38 continues on to the picture printing aperture. Before it arrives at the aperture it is met on one side by the green negative 33 and on the other side by the red negative 34 and the three lms pass over and are driven together by the drive sprocket 35. Forming a loop Se, the three films next pass to the light change contacting device 3l' which initiates the change of illumination of the printing aperture in response to an interruption in the film odge located at a change of scenes, as will hereinafter be explained in detail. The red negative only passes through the contacting device 3l, the green negative and the raw stock passing over the top thereof. Thence the three films are intermittently drawn past the picture printing aperture 38 by means which will hereinafter be described in detail, pass over the driving sprocket through the positively driven sprocket mechanisr. du, and separate to pass to their respective take-up reels. At the printing aperture one side of the positive film is exposed through the green negative by light which comes from a lamp within the lamp-house fil, and the other side of the positive film is simultaneously exposed through the red negative by light which comes from a lamp within the lamp-house ft2. The illuminations on the two sides at the aperture due to the two lamps are very accurately controllable in a manner which will hereinafter be described in detail.

The mechanism which the sprockets and take-up reels are driven is best illustrated in Figs. 2, ll, and l5 and is as follows. The electric motor d5, which is preferably a substantially constant speed motor, is mounted on the frame by means of bracket il@ and provides the motive power for the printer. The shaft of the motor is connect d through spur gears Vi and @it with a horizontal shaft is journaled in the frame and carrying the flywheel 5d. In geared connection with the shaft Si is a vertical shaft 5l geared to the shaft of sprocket 35, and geared to shaft 52 is also the vertical shaft 53 which is in geared connection with the shaft 5d on which is carried the sprocket which drives the nlm at conste-.nt velocity past the sound printing aperture The shaft E/.l also carries a flywheel 5l pulley 5S which drives the sound negative take-up reel 29 through belt 59. In geared relation to the shaft 13S is also vertical shaft 60 which is geared to another vertical shaft E! which in turn is geared to the various sprockets of mechanism di! and also to the pulley shaft 62 carrying pulleys which drive the take-up reels 23, 25, and 2l through belts 53, G4, and S5.

rfhe three films E@ and 34 are moved intermittently past the picture printing aperture by a mechanism which causes two claws to move substantially horizontally with respect to the film, into perforations at opposite edges of the films and move vertically downward relative to the printing aperture until the lms are in position for printing, whereupon the claws are withdrawn from the perforations substantially horizontally and moved vertically upward to be in position to again engage the film after an exposure has been completed. Referring particularly to Figs. 3, 4, and 15, it will be seen that on the horizontal shaft 49 is a heart-shaped cam 68 engaged by a partially rectangular follower G9 which carries a structure 10 vertically up and down when the cam 68 is rotated. Mounted on structure 10 and movable horizontally to and from the films are two claws 'H and 'l2 whose ends are adapted to engage perforations at opposite edges of the films to move them. The ends of the claws are preferably so shaped that one claw fully fits the perforations, while the other claw nts the perforations in a direction longitudinal of the lm only. By the use of claws of this shape the three films are accurately registered with respect to one another before the claws are removed, which is Very essential in producing good colored pictures, yet shrinkage of the film is permitted by reason of one claw fitting only in the longitudinal direction. claws 1| and 12 are moved into and out of the film perforations by the elongated pinons 'i3 and 14, respectively, which are meshed with racks constituting the outer sides of the claws. The pinions 13 and 14 are journaled on the frame and are rotated by engagement of eccentric pins and 16 with peripheral grooves '1i and 'i8 in the cylinders 19 and 80. The grooves '.'i and 18 are so shaped and oriented that while the follower S9 is at the top of its stroke, the pinions 13 and 14 are rotated to cause the claws 'll and 12 to be inserted in the perforations; and while the follower 69 is traveling downward the pinions 13 and 14 are stationary. When the follower 58 is at the bottom of its stroke, the pinions 'i3 and 14 are rotated so as to withdraw the claws ll and 12; and while the follower 68 is moving vertically upward, the pinions are again stationary. By use of this mechanism, the iilm engaging claws are moved in a substantially rectangular orbit, and the films are brought to rest vertically before the claws are withdrawn. For this reason accurate vertical registration of the three films is secured without the necessity of registration pins being present in the perforations at the time of exposure.

At the picture printing aperture 38 is a plate 83 against which the red negative bears. As may best be seen in Figs. 3, 4, and ll., this plate, together with its supporting structure, and the light tunnel 84, shutter housing 85, lamp-house 42, and connected parts are pivoted on the pivot 86, mounted on the frame, and may be dropped down to permit threading of the printer. On the opposite side of the three films and resiliently bearing on green negative 33 adjacent the aperture is the pressure plate 81 which insures positive contact between the three films during exposure. During movement of the iilms past the aperture, the pressure plate is backed away by means of four pins 88 which pass through holes in plate 83 and engage the face cf the pressure plate 81 beyond the edges of the film. The pins 88 are carried on two strips 89 which at their mid-points are pivotally mounted on bifurcated lever 90 pivoting about a fulcrum at 9| on the supporting structure 92 for the plate 83. The upper end of lever 90 carries an arm 93 ending in a cam follower 94. This cam follower 94 rides on a peripheral cam 95 cut on the cylinder 89, seen in Fig. 13, and the cam 95 is so shaped that when the iilm is about to be moved the lever 90 is rotated sufficiently to cause the pins 88 to be pressed against the pressure plate 8l, so as to relieve the pressure on the film, and after the film has come to rest, the pins 88 are withdrawn, allowing the pressure plate to again press against the films. To permit the threading of the printer Without interference from the pressure plate, I provide two projections $25 and 9T attached to the pressure plate 8l and extending back therefrom, and having ends turned into directions parallel with the pressure plate as seen in Figs. 3 and 15. I also provide reds 98 and 93 slideable in the frame and having bevelled ends and lill adapted to engage the inner faces of the right-angularly turned ends oi' projections 35 and 9? and pull the pressure plat-e away from the film. The rods 98 and 99 connected by member |82 which is moved by a pi'n |83 slideably engaged by the lever 94 pivoted about the pivot H15. Raising the handle portion of the lever IEM causes the pressure plate to be retracted.

Exposure of the emulsion of the positive stock adjacent the red negative 34 takes place through the red negative by reason of light from the electric lamp ii mounted in the lamp-house 42. As seen in Figs. 3 and 4, the light passes through an opening III, through a light change device generally indicated by numeral H2, hereinafter described in detail, through the opening l I3 in shutter H4, and through the light tunnel 84, to the films. Exposure of the emulsion of the positive stock adjacent the green negative 33 takes place through the green negative by reason of light from the electric lamp H6 in lamphouse 4l. The light from lamp H6 passes through the opening lll, through the light change device Elli, similar to the device H2, through jthe opening H9 in shutter l2() and through the light tunnel lEl, to the films. In this ease the light tunnel S23 is partly formed hollow structure iii supporting the lm moving claws. Hence this portion 'J8 enclosing part of the light tunnel reciprocates vertically which explains the necessity for its being vertically elongated, as best shown in Fig. 3. In order to improve the uniformity of illumination at the films I may provide frosted glass diffusing plates 22 and 23 in the paths of light from the two lamps, or I may employ in these positions filter plates to enable printing to be done with any selected colors of light. The .shutters l i4 and 529 are thin dises having arcuately disposed openings H3 and HS, respectively, adapted to uncover the respective sources of light. The shutters are mounted to be turned by the same shaft 524 and are driven. continuously by means the geared connection 25 with the shaft 60. The openings M3 and l5!! are so positioned that they uncover the respective sources ilil and H55 when the films are in position for exposures to be made. Since the shutter housing 85 must move with the plate t3 and the attached structure to permit the iilms to be threaded, I provide a break in the shutter shaft near shutter l i4 at 25, the two ends of the shaft at the point of disconnection having surfaces that lock with one another in one position. to provide a driving connection when the shutter is in operative position. A spring l2'I assures continuous engagement of .gay

the connection |26 while the shutter is in operative position. The lamp |||J is in series with rheostat |28, and the lamp ii is in series with the rheostat |29, each of these circuits being connected to a source of electricity which is preferably accurately controlled in voltage. By Variation of the rheostats |28 and |29 the luminous intensity of the respective lamps may be adjusted to the desired values.

In order to assure constancy of the sources of light ||0 and lit I provide means for continuously indicating the luminous intensity of the lamps. Attached to the lamp-houses 42 and 4| and connected to the interiors thereof by openings |32 and |33 respectively, are cases |30 and |3|, respectively, containing matched lightmeasuring cells 34 and |35, respectively. While other types of light sensitive cells may be employed, I prefer to employ cells of a photo-voltaic type such as that known as the Photronic cell, for these cells generate their own electromotive force in response to light and are stable and of relatively long life. The cell |34 is electrically connected to the indicating meter |33 and the cell |35 is connected in circuit with the meter |31. By this means, the indications of meters |35` and |37 are a measure of the amounts of light falling upon the respective cells i3d and 35, which is turn are proportional to the luminous intensities of the respective sources and H6. Thus, in my printer, it is impossible for a lamp to gradually lose intensity or suddenly fail without this change being indicated. This device makes possible the accurate balancing of illumination on the red and green negative and permits this balance to be continuously maintained.

An important feature of my invention is the means by which I change the illumination at the aperture from scene to scene of the picture being printed. In the path of the light from lamp i i, in front oi opening il are two adjacent relatively movable plates ist@ and lili both preferably mounted slidably in the frame, as shown in Figs. Li, 5, 6, 8 and 9. Each of these plates has one or more apertures preferably comprising one or more spaced parallel slits M32 opposite the opening through which light passes to the iilms. The slits M2 are preferably made .025 inch in width and the distance between adjacent edges of any two slits is preferably made .021 inch. Thus, if the two plates are placed against one another with their slits 42 parallel and if they are then positioned so that the slits perfectly register with one another the maximum amount of light will pass through, there being openings of .025 inch; while if the plates are slid one along the other to the point where the opaque portions of plate |l| are entirely overlying the transparent portions of plate Idil, there will be only .G25-.021:.004 inch openings available for transmission of light and illumination on the lm will be reduced to the minimum possible with this combination of slits. If the relative lateral positions of the two plates M9 and lill are progressively changed between these two limits a smooth variation in the intensity of illumination on the printing aperture is obtained. I preferably provide means for varying these positions in 2l steps providing 22 intensities of illumination.

This variation is accomplished by providing on the plate 49 a jaw 43 in the plane of plate lll! and providing spacers of measured thickness adapted to enter between the jaw |43 and the similar jaw i154 constituting the end of plate Mi.

A spacer |555 is xed to the plate Mil in the plane of plate Uil and serves to always maintain a spacing between the jaws |43 and |44 which will permit the easy entrance of the metering spacers therebetween. A pin |63 is fixed in plate Hi and another pin |69 is fixed in plate |4| and adapted to pass through hole |33 in plate |49. A spring iii, seen in Fig. 4, is attached at opposite ends to pins |53 and it and acts to raw the jaws M3 and |134 together in contact with the metering spacers. The metering spacers |46 are preferably cylindrical plugs, like that shown in Fig. l0, the upper portion till oi which is smooth and accurately of a certain diameter corresponding to a numeral which is for convenience marked on the top. The lower portions of the spacers M5 are of uniform size and are split to be retained by friction in holes provided for that purpose. A rotary member in the shape of a disc Hi8 is mounted on the shaft |69 so that it rotates with its periphery just out of contact with the jaws |43 and ills, as shown in Figs. 5 and 6. In the periphery oi the disc M8 are a large number or uniformly spaced holes |53 into which the metering spacers MG are adapted to be inserted and retained by friction. When the spacers |46 are so inserted in the disc |48, and the disc is intermittently rotated, the spacers successively space the jaws apart distances which correspond to the diameters of the respective spacers ifs. As each spacer comes between the jaws |43 and U51, then, the slits |432 of the plates Mii and lili are laterally adjusted relative to one another so as to change the aperture area common to both plates and thus to let more or less light through, depending upon the diameter of the particular spacer. It will. be observed that since both plates itil and are made movable, their relative lateral positions depend only upon the thickness of the spacers ifi-t and are not aiected by any misalignment or lateral shifting of disc Hi8.

The disc MS is designed to be retained stationary with one of the spacers between the jaws until it is desired to change illumination when, in response to an electric current, the disc is caused to be rapidly rotated to bring the next spacer between the jaws. The disc |48, rotatably mounted on shaft Mil, is retained on the shaft by the knurled nut ll and is connected for rotation with the ratchet wheel 52 by the pin i522 carried by the wheel and extending into a hole in the disc |48. The ratchet wheel 552 is provided with peripheral teeth |54 which are engaged by pawl 55. Back of the ratchet wheel and in a recess in the frame is a spiral coil spring E56 which is attached at |5'i to the shaft His and at the other end to the ratchet wheel at |58, seen in Fig. '7. The action of the spring is to tend to cause rotation of the disc |48 in the direction shown by the arrow in Fig. 5. The shaft |43 is restrained from turning in the frame by clamping it by means of screw |59. The heel |63 of the pawl |55 is normally held in engagement with one of the teeth of the ratchet |52 by means oi the spring |E| so as to prevent rotation of the ratchet, and the pawl is so located that it stops the disc Hi8 in such a position that one of the spacers M5 is between the jaws |43 and IM. the short shaft |52 which passes through the adjacent frame and is turned by arm |63 whose end is acted upon by a yoke |64 on the plunger |55 of an electromagnet |66, as shown best in Fig. '7. Upon energizing the coil of the electro- The pawl |55 is mounted on magnet |66, the plunger is drawn in, swinging the arm |63 down, lifting the heel |60 of pawl |55 out of engagement with the ratchet and tipping the toe |61 of the pawl into engagement with the ratchet so as to limit the rotation of disc |48, which promptly ensues, to only slightly more than sulicient to permit the heel of the pawl to avoid the tooth with which it has been in contact, when next the heel engages the ratchet. When, now, the current through the electromagnet coil is broken, the pawl |55 will rotate so as to cause toe |61 to lift and heel |60 to drop into engagement with the ratchet, whereupon the disc |48 will rotate slightly until heel |60 stops the disc by engagement with the tooth of ratchet |52 which is immediately next to the one previously engaged. Thus, by momentarily making and breaking the circuit of the electromagnet coil, the disc |48 is rotated by one step to bring a new spacer |46 between the jaws |43 and i44. To limit the rotation of the disc to one revolution, I provide an annular groove |38 in the back of ratchet wheel |52 which is not quite a complete circle. Into the groove |38 projects a screw |39 which is secured in the wall of the ratchet casing. The ends of groove |38 are adapted to engage the screw |39 in the iirst and last operative positions of the disc |48.

In the printing of motion pictures including a plurality of successive scenes, the intensity of illumination at the printing aperture may be changed from one scene to the to take account oi varying negative density by inserting suitable metering spaces |46 successively around the disc |48 and causing the disc to be advanced one step each time one scene changes to the next. This change is ordinarily initiated by the passage past a contacting device 31 of a notch |12 in the edge of the negative film located near the point of change from one scene to the next. In my printer I prefer, when printing from two negatives, to -notch only the red negative and pass it alone through the device 31. The contacting device 1 is illustrated in Figs. l2 and 14 and may comprise a plate |13 having a track |14 on which the lm 34 slides, the plate being undercut in the picture area, and being provided with a hinged gate |15 with a catch |16` which connes the red negative film in a plane during the passage through the device. The positive stock and the green negative pass over the contacting device on the track |84. Beneath the plate |13 and confined in a recess thereof by insulating cover |11 is a sliding member |19 continuously urged by spring |19 toward the notched edge of lm 34. 'Ihe member |18 has mounted near its end adjacent the notched edge of lm 34 a rotatable roller |80 which is adapted to engage the edge of the lm 34 and momentarily move to the left and back (Fig. 12) when a notch |12 passes by. The sliding member |18 carries at its other end a downward projection |83 of insulating material which is adapted to engage contact lill and move it into contact with contact |02 when roller 80 enters notch |12.

Normally, when the roller |39 riding on the edge of film 34, the contacts |8| and |82 are separated. The contacts |8| and |82 are connected in series with a source of electric current and the coil of electromagnet |66. When, therefore, a change of scene occurs and a notch |12 passes the roller |80 the contact Isl-|82 is made and current momentarily passes through the coil of the electromagnet |66. The disc |48 is moved by one step and a new metering spacer |46 comes between the jaws |43 and |44 to effect a relative positioning of the slits |42 of plates |40 and |4| which allows light to pass in an intensity determined by the diameter of the spacer |46 which was inserted in the particular position of disc |46 which is now effective. In this manner a large number of scenes may successively be printed, each with its own suitable illumination intensity, the number of scenes being only limited by the number of holes avail-- able for spacers |46.

'Ihe light change device i i 2 employed to change the illumination at the aperture coming from lamp H0 is similar and is operated similarly to the light change device ||8 just described.

In order to provide against accidental exposure of the positive stock by swinging down the light tunnel 84, lamp-house 42, and associated parts, I provide special means now to be described. As seen in Figs. 4 and 6, adjacent to the light change device ||8 and between it and the housing for shutter |20 is a slidable plate |90 having a handle |9| attached thereto. In the plate |99 is a ruby glass window |92 which is so located as to cover the slits in light change device M3 and permit the transmission of only red light to the light tunnel |2| when the plate |90 is pulled outwardly to its extreme position. Projecting into a slot |93 in plate |99 is the handle or a toggle-type electric switch |94, the slot being so located that when the plate is pulled outwardly the switch is operated to break the connected circuit. The switch |94 is connected in circuit with the lamp ||0. The result, then, o1 pulling the handle |9| together with its attached plate |83 outwardly to the extreme position is to eliminate entirely any light from lamp Il@ and to permit only red light to pass to the aperture to aid in threading the printer. The lamp-house 42, light tunnel 84, and associated parts can only be swung down around pivot 86 if the handle |9| is pulled out to its extreme position in which all white light is prevented from coming from the printer. The house 42 and associated parts are locked in operative position by the end of lever |95 which is held under the large head of a screw |96 in the frame, as seen in Fig. 11. The lever |95 pivots about the pivot |91, and at its end engages a substantially horizontal arm |98 pivoted at |99 on the frame and urged downwardly by spring 200. The lever |95 is prevented from moving to the unlocked position by the slidable bar 203 which engages the under side of the locking end of the lever. Slidably engaging in a slot thereof a pin xed in plate |90 is a lever 204 pivoted at 205, as shown in Fig. fi, the end of which lever resides between pins 206 on bar 203 and causes the bar to be moved toward the right in Fig. l1 when the handle |9| is pulled out. Thus, when the handle |9| is pulled outwardly to its extreme position, the bar 203 is removed from beneath the lever |95, permitting the latch to be unlocked. In this position of the bar 203, the foot 202 of pawl 20| falls into the notch 201 in the upper side of bar 293 and prevents the bar 203 from being slid back to the left until the lever |95 is brought into the locked position. As the end of lever i95 is brought up into the locked position, it engages the end of arm |98 and a finger-like projection on the under side of the arm |98 hooks the pawl 20| raising its foot out of notch 201, whereupon the handle |9| can again be pushed in to cause both sides of the printing aperture to be illumined. It will be observed that by this means I make it impossible for any light to come from the lamp iid, or white light to come from the lamp llt, when the light tunnel 8f3, lamp-house 42, and associated parts are swung down out of operative position.

It is understood that the various mechanisms herein employed in connection with a printer ior printing opposite sides oi a color nlm, such as my means for accurately indicating and for changing printing illumination, my means for preventing accidental exposure of the lm, etc., may equally well be applied to a printer making a single exposure. And various changes and modications in design and construction from the embodiment illustrated herein may also be made by those skilled in the art without departing from the spirit of the invention defined by the appended claims.

I claim as my invention:

l. In a printer for photographic lm including a source of light for illuminating said film, two adjacent members relatively movable in a direction transversely of the path of light illuminating said nlm and each apertured in said path, said two members having opposing surfaces which are arranged normal to the direction of their relative movement and which are adapted to be spaced apart predetermined distances by metering spacers, resilient means urging said opposing surfaces toward each other, a movable spacer supporting member carrying a plurality of removable metering spacers adapted upon movement of said spacer supporting member tosuccessively enter between said opposing surfaces, a spring drive tending to produce movement of said spacer supporting member, a ratchet connected for movement with said spacer supporting member, a pawl engaging said ratchet, and means for operating said pawl to permit movement of said spacer supporting member a distance required to introduce a different metering spacer between said opposing surfaces.

2. In a printer for motion picture film including means for moving lm through the printer and a source of light for illuminating said lm, two adjacent members relatively movable in a direction transversely of the path of light illuminating said nlm and each apertured in said path, said two members having opposing surfaces which are arranged normal to the direction of their relative movement and which are adapted to be spaced apart predetermined distances by metering spacers, resilient means urging said opposing surfaces toward each other, a rotary member carrying a plurality of removable metering spacers adapted upon rotation oi' said rotary member to successively enter between said opposing surfaces, a spring drive tending to produce rotation of said rotary member, a ratchet connected for rotation with said rotary member, a pawl engaging said ratchet, an electromagnet ior operating said pawl to permit rotation of said rotary member through an angle required to introduce a different metering spacer between said opposing surfaces, and means to momentarily energize the coil of said electromagnet to effect operation oi said pawl in response to an irregularity in the passing iilm.

3. In a printer for motion picture i-llm including means for moving lrns through the printer and a source of light i'or illuminating said film, two adjacent plates relatively movable in a lateral direction and each having a plurality of parallel slits therein in the path of light illuminating said film, the slits of one of said members being adapted to transmit light passed by the slits of the other of said members, opposing parts oi said two members forming jaws adapted to be laterally spaced apart predetermined distances by metering spacers, a spring urging said jaws together, a spacer limiting the nearness of said jaws, a rotary disc carrying on its periphery a plurality of removable metering spacers adapted upon rotation of said disc to successively enter between said jaws, a spring tending to produce rotation oi said disc, a ratchet connected for rotation with said disc, a pawl engaging said ratchet, an electromagnet for operating said pawl to permit rotation oi said disc through an angle required to introduce a diierent metering spacer between said jaws, and means to momentarily energize the coil of said electromagnet to eiect operation of said pawl in response to an irrregularity in the passing film.

li. In a printer i'or photographic iilrn including a source of light for illuminating said lm, two adjacent members relatively movable in a lateral direction and each apertured in the path of the light illuminating said rllm, a rotary member carrying on its periphery a plurality of removable radially extending spacers, a pair of jaws adapted to engage opposite sides of one of said spacers and connected to said members for control of the relative lateral position oi said members, and means for intermittently rotating said rotary member to successively bring said spacers between said jaws.

5. In a printer for photographic film including a source of light for illuminating said nlm, two adjacent members relatively movable in a lateral direction and each having a plurality of parallel slits therein in the path of light illuminating said nlm, the slits of one of said members being adapted to transmit light passed by the slits of the other of said members, a rotary member having radial recesses in its periphery, a plurality of radially extending pins frictionally retained in said recesses, a pair of jaws adapted to engage opposite sides of one of said pins and connected to said members for control of the relative lateral i position of said members whereby the light passing through said members is determined by the thickness of said pin, and means for intermittently rotating said rotary member to successively bring said pins between said jaws.

CHARLES F. JONES. 

